2
Schematic Checklist
2.1 Power Supply
For details of using power supply pins, please refer to Section
Power Scheme
in
.
2.1.1 Digital Power Supply
Pin 11 and pin 17 are the power supply pins for RTC IO and CPU IO respectively, in a voltage range of 3.0 V
~
3.6 V. We recommend adding 0.1
µ
F capacitors close to each digital power supply pin.
When working as an output power supply pin, VDD_SPI can be powered by VDD3P3_CPU via R
SP I
(nominal 3.3
V). Therefore, there will be a voltage drop on VDD_SPI to VDD3P3_CPU. We recommend adding a 1
µ
F filter
capacitor between VDD_SPI and ground.
When not working as a power supply pin, VDD_SPI can be used as GPIO11.
5
5
4
4
3
3
2
2
1
1
D
D
C
C
B
B
A
A
NC: No component.
The values of C8, L2 and C9
vary with the actual PCB board.
The values of C1 and C2 vary with
the selection of the crystal.
The value of R1 varies with the actual
PCB board.
GPIO19
CHIP_EN
GPIO4
GPIO5
GPIO6
GPIO7
GPIO8
U0RXD
GPIO18
LNA_IN
GPIO9
GPIO10
GPIO0
GPIO1
SPICS0
SPID
SPIQ
SPICLK
SPIWP
SPIHD
GPIO2
GPIO3
RF_ANT
U0TXD
SPICLK
SPICS0
SPIHD
SPIWP
SPID
SPIQ
GND
VDD33
GND
GND
GND
GND
GND
GND
GND
GND
VDD33
GND
GND
GND
VDD33
VDD_SPI
VDD33
GND
VDD_SPI
GND
GND
GND
GND
C1
TBD
C9
TBD
U3
FLASH-3V3
/CS
1
DO
2
/WP
3
G
N
D
4
DI
5
CLK
6
/HOLD
7
V
C
C
8
R4
0
R7
0
R6
0
C12
0.1uF
R
1
ANT1
PCB_ANT
1
2
R5
0
C10
0.1uF
C3
1uF
R2
499
R3
0
L1
2.0nH
C2
TBD
C8
TBD
C6
0.1uF
L2
TBD
C5
10uF
C4
100pF
C7
0.1uF
C11
1uF
U2
ESP32-C3
LNA_IN
1
VDD3P3
2
VDD3P3
3
XTAL_32K_P
4
XTAL_32K_N
5
GPIO2
6
CHIP_EN
7
M
T
M
S
9
M
T
D
I
1
0
V
D
D
3
P
3
_
R
T
C
1
1
M
T
C
K
1
2
M
T
D
O
1
3
G
P
IO
8
1
4
G
P
IO
9
1
5
G
P
IO
1
0
1
6
VDD3P3_CPU
17
VDD_SPI
18
SPIHD
19
SPIWP
20
SPICS0
21
SPICLK
22
SPID
23
SPIQ
24
U
0
R
X
D
2
7
U
0
T
X
D
2
8
X
T
A
L
_
N
2
9
X
T
A
L
_
P
3
0
G
N
D
3
3
GPIO3
8
V
D
D
A
3
2
V
D
D
A
3
1
G
P
IO
1
9
2
6
G
P
IO
1
8
2
5
U1
40MHz(±10ppm)
X
IN
1
G
N
D
2
X
O
U
T
3
G
N
D
4
R8
10K
Figure 2: ESP32C3 Family Digital Power Supply Pins
Notice:
When VDD_SPI works as the power supply pin for embedded and external 3.3 V flash, VDD3P3_CPU should
be 3.0 V or above, so as to fall into flash’s operating voltage range.
2.1.2 Analog Power Supply
Pin 2, pin 3, pin 31, and pin 32 are the analog power supply pins, working at 3.0 V
~
3.6 V. Please note that when
ESP32-C3 family works in transmission (TX) mode, the instantaneous current is higher and may cause a power
rail collapse. Therefore, it is highly recommended to add a 10
µ
F capacitor to the power trace, which can work in
conjunction with the 0.1
µ
F capacitor. In addition, a LC filter circuit needs to be added near pin 2 and pin 3 to
suppress high-frequency harmonics. The inductor’s rated current is preferably 500 mA or above. Refer to Figure
and place the appropriate decoupling capacitor near each analog power pin.
Espressif Systems
6
ESP32-C3 Family Hardware Design Guidelines V1.0
